Cross-references are realized in Metanorma AsciiDoc by assigning an anchor to the block to be referenced, and writing a cross-reference containing that anchor ID:

= Target clause

The requirements are...

= Reference clause

As seen in <<anchor-id>>...
See Anchor ID syntax for allowed characters in anchor IDs.
Cross-reference text in Metanorma adheres to guidance given in ISO/IEC DIR 2 for internal cross-references, in order to guarantee unambiguous referencing.

In particular, if a formula, example, figure, list, list item or table is cross-referenced outside its (sub)clause, the clause containing the item is always given in the cross-reference, unless the item is being referenced in the same clause.

In the case of notes, the containing clause is extended to containing example, figure or table.

For example, in the Metanorma ISO Rice model sample document formula B.1 is defined in Annex B.6, and is referenced in B.6 and B.7.

In the Rice model document published by ISO, both instances are cited as “Formula (B.1)”. However, Metanorma follows ISO/IEC DIR 2 in citing the former as “Formula (B.1)”, but the latter as “B.6, Formula (B.1)”.

In this sense, Metanorma is “more royalist than the king” in applying formatting rules and validation—which is what you would want of a computer-based tool.

The label of the item cross-referenced, the use of brackets, and the containing reference are all taken care of by Metanorma; the document author needs only give the item identifier in the AsciiDoc source (e.g. \<<formulaB-1>> generates either “Formula (B.1)” or “B.6, Formula (B.1)”, depending on where in the document it occurs.)

If the cross-reference is given with droploc% as its text, then the label and prefix are dropped: the cross-reference value is given in isolation [added in].

This can be done for example for ranges:

Clauses <<context,droploc%>> to <<improvement,droploc%>>

to be rendered as e.g.

Clauses 7 to 9

Anchor ID syntax

Anchor IDs of any type (cross-references, items, bibliographies, etc.) are directly converted into XML, and therefore must not contain the following:

  • colons

  • whitespaces or;

  • words starting with numbers.

These cases are not supported in XML; permitted characters are specified by the NCName attribute for Namespace Declaration.

Colons in cross-references are used for indirect cross-references between files in the same collection, to delimit namespaces and containers from anchor IDs [added in].


Normally in AsciiDoc, any text in a cross-reference that follows a comma constitutes custom text for the cross-reference.

So a cross-reference <<ISO7301,the foregoing reference>> would be rendered as “the foregoing reference”, and hyperlinked to the ISO7301 reference.

In Metanorma AsciiDoc cross-references, bibliographic localities (e.g. page numbers, clause numbers) can be added directly after the comma, as part of the cross-reference text.

This differs from the normal AsciiDoc treatment of custom text.

EXAMPLE: “ISO 7301, Clause 2, Table 1a, pp. 7-9” would be expressed as:


List items

List items can be cross-referenced by inserting a bookmark at the very start of the list item:

. Ordered list
.. [[id1]] This is the first list item
... [[id2]] This is a list sub-item

Definition List Terms

Definition list terms can be cross-referenced by inserting a bookmark at the very start of the term [added in]:

[[id1]]Term 1:: Definition
[[id2]]Term 2::: Another Definition

Hyperlinks to URIs can have alt text, which is used in accessibility (corresponding to the HTML a@title attribute).

This is specified by appending ,title=…​ after the text in the URL macro in Metanorma AsciiDoc:[text to go into the hyperlink][text to go into the second hyperlink,title=This is a tooltip for the link]

External references

In localities and locality values, anchor can be integrated in citations of documents via references.

For example:


will generate a hyperlink to the element with ID xyz in document ISO7301. This convention is necessary for cross-references between documents in a Metanorma document collection.

Outside of that, Metanorma will process cross-references to anchors within external documents just like typical AsciiDoc.



will be processed as a link to anchor #b in document document1.adoc.

If the reference uses the .adoc suffix, as in the example above, it is stripped in Metanorma XML and substituted with the extension of the current document type during document generation.

The above example is rendered in Metanorma XML as <xref target="document1#b">, in HTML as <a href="document1.html#b">, and in PDF as <a href="document1.pdf#b">.